Grinding mill



Oct. 24, 1939. L. DoTzER ET AL 2,176,892

GRINDING MILL GI'ORG D. HUGO ArroRNEYS Oct. 24, 1939. DQTZER HAL y 2,116,892

GRINDING MILL Cet. 24, 1939. l.. DOTZER "Er AL 2,176,892

GRINDING MILL Filed Feb. e, 193s e sheets-sheet 4 INVNTORl Eo/m20 .orzE/e GEORGE D. H060 Oct. 24, 1939. L. DOTZER ETAL 2,116,892

GRINDING MILL Filed Feb. 8, 193s e shets-sheet 5 INVEN TOR.

EON/(R0 DoTzLj/ 234 BY 650365 o H060 MM A TTORNEYS' 0f.24, 1939. DOTZER ETAL 2,176,892

` GRINDING MILL Filed'Feb. 8, 193e e sheets-sheet 6 gli [N VEN TOR. E0/mea ./JoTzf/e 745 BYaL-01665 0. H060 @gwn ATTORNEYS.

Patented Oct. 24, 1939 GBINDING MILL Leonard Dotzer, Brooklyn, N. Y., ant'. George D.

Hugo, Seattle, Wash.

Application February 8, 1936, Setial'No. 62,952

7Claims.

This invention relates to grinding mills, and more particularly to improvements in mills of that kind used for the reducing of a solid to a desired degree of iineness by a plurality of reductions, or grindings. While the present invention deals more particularly with machines for grinding solids of vegetable origin, such as cocoa nibs, it is not to be construed as being limited thereto, but, rather, it is to be understood as l0 applicable, without material modification, to the y grinding of solid, semi-solid, pasty and liquid substances -of vegetable, mineral, or of other origin. l

ln order to impart a better understanding of the present improvements', it will here be explained that grinding mills of thetype to which the present invention applies, as heretofore' used, comprise grinding elements, or stones, arranged in pairs; that is, requiring two stones for each reduction. I'hese grinding elements, in their most common embodiment, comprise fiat faced stones. mounted face to face-in axial alinement, and relatively revoluble. Generally one stone is held stationary while the other `is rotated,

although they both may be rotated in opposite directions. ,The coacting slu'iaces of paired stones are grooved, ribbed or otherwise processed, whereby to cause the material fed between them for grinding to be advanced outwardly between 3o the stones and ground or reduced during its progression.

Furthermore, in the prior art mills, as employed for instance in the grinding of chocolate, or cocoa, and wherein provision is made for a plurality of reductions or grindings, two stones are employed for each reduction. Thus, for two reductions, four stones are employed, and for three reductions six stones are employed, and it has always been the practice heretofore to 40 feed the material from the center outwardly.

In view of the above, and in viewofthe fact I that it is very desirablethat the weight and size of such mills be reduced as much as possible without loss of efciency or impairing durability,

as well as it being desirable also to provvidefor greater capacity and eiliciency in operation, at

a lower cost, it has been the principal object of this invention to provideffor the utilization of grinding disks or stones in an arrangement whereby the 'opposite sides ofthe intermediate stones of an axially alined set of three or more,

are made available for and are in the grinding of the material passed the mill.

It has also been an obiect o this invention to 55 provide a novel manner of grooving the adjacent or -coacting surfaces of grinding stones, whereby the material being ground maybe causedA in certain instances to progress from the outside toward the center of the set; that is, acentripetalA movement, as diierentiated from a centrifugal 5 travel, so that in a mill arranged for a plurality of reductions, the material may be caused to iiow alternately from and toward the axis as it progresses from one set of stones to the other.

Still another object of the invention resides in a; modication wherein the grinding stones are disposed in vertical planes instead of being horizontally disposed.

A further object of the invention resides in the manner of mounting the stones of a mill whereby coacting grinding surfaces 'are retained at all times inparallel relation, as diierentiated from means provided in prior art devices whereby 'one of the stones is left free for universal movement to automatically adjust itself to irregularities of the other which might result from varjious causes.

Still another object of the invention resides in the provision of means for eecting a yielding and adjustable pressure ofone stone toward its companion stone to regulate the grind.

Still another object is to provide novel means for adjusting the stones of a mill to spaced relation and for readjusting them to grinding relation in a predetermined order. Y

Another object resides in the provision oi novel means for a forced delivery of partly ground plastic material from one set of stones to another.

Still further objects of the invention reside in those details of construction that permit of an easy and ready removal, or replacement, of one unit of a machine without interference with others.l l

It is also an object to provide aomachine for the grinding of cocoa, chocolate and the like. but adaptable also to the grinding of paints,`mus tard, lead, flour and the like, and requiring only minor modifications or alterations to change it from one to the other.

Other obiectslof the invention reside in the novel details of construction. in the combination of parts and in theirmode of operation, as will hereinafter be described.

In accomplishing these and other objects of the invention, 'we have provided the improved details of construction, the preferred forms ot which are illustrated in the accompanying drawings. wherein Fig. 1 is a side elevation -of one type of grinding mill embodied by the present invention.

Fig. 2 is a vertical, cross section view of the same, as seen in its central axialplane.

Fig. 3 is a top view of the machine.

Fig. 4 is a partial front elevation, showing the drive shaft and gearing'for the rotated stones of the machine.

Fig. 5 Ais a fragmental, perspective View, showing one manner of grooving or processing a surface of a stone of the machine.

Fig. 6 is a horizontal section, taken on the section line 6 6 in Fig. 2.

Fig.7 is a horizontal cross section taken on section line 1 1 in Fig. 2.

Fig. 8 is a sectional detail illustrating the coacting cam surfaces for lifting the upper stone of the lower unit.

Fig. 9 is a similar lView showing the coacting cam surfaces for lifting the intermediate stone of the lower unit.

Fig. 10 is a vertical cross section of an alternative construction utilizing an under feed for plastic or semi-liquidl materials.

Fig. 10a is a detail of a mounting for a stationary stone in the machine of Fig. 10.

Fig. 10b is a detail of a stone lifting means in the same machine.

Fig. 11 is a vertical cross section of a machine of an alternative type of construction wherein the material to be ground progresses outwardy and then inwardly between successive grinding stones of a series.

Fig. 12 is an elevation of a plural grind, vertical stone mill. Fig. 13 is an enlarged cross section on line I3-I3in Fig. 12. l

Fig. 14 isl a planview illustrating the method of grooving the co-acting surfaces of stones to effect a centripetal movement of ground material.

Referring more in detail to the drawings- In one of the present forms of construction, embodied by this invention, as shown in Figs. 1 to 9, inclusive, there is a xed, or stationary, frame structure in which two grinding units are operatively mounted. Each of these units, as will later be described, employs -three stones with four coacting grinding surfaces. The two units are independent of each other, insofar as their mounting in the frame is concerned, thus tov provide for independent removal or replacement, but both units of thelzmachine are here arranged to be driven from acommon source of power and provision is made for relaying the partially ground material from one to the other.

The frame structure of this machine comprises four vertical standards, I, tubular or of other cross sectional form, forming the corners of a rectangular support. At their lower ends, these standards are fixed in bases 2 which may be bolted or otherwise secured to the floor, or other support provided for the machine. At their upper ends, the standards are rigidly xed in a horizontal spider 3, and intermediate their ends they are likewise joined by a horizontal spider 4. Each of the spiders, 3 and 4, comprises radially extending legs equipped at their ends with` suitable mountings 5 which receive, and in which the standards I are clamped.

Machines of this kind may comprise a plurality of units, and each might comprise two or more stones, according to the capacity desired. In the machine of Figs. 1 and 2, the grinding units are of somewhat diierent construction. For easy referencef the upper unit is designated in its entirety by reference character A, and the lower unit is designated in its entirety by reference character B; the upper unit A being identified as a single grind, double face direct discharge machine, and the lower unit B being identified as a double face, center return,successive grind machine. In accordance with a stated object of the invention, these two units are independent of each other in mounting, and are demountable from the frame to facilitate repair, regrooving, or

replacement of stones, and either unit may be removed without interference with the other.

As will be best understood by reference to Fig. 2, the upper unit A is operatively supported in the machine upon a pair of parallel channel beams 1-1, that are xed horizontally upon the inside of the frame standards. Preferably, the means of attaching the beams 1` comprises clamp bands 8 which embrace the standards I and are bolted at their ends to the beams.

The lower unit B, likewise, is supported upon parallel, horizontal beams I0, here shown as resting upon the bases 2 and secured to the vertical standards by clamp collars II that embrace the latter and are attached by bolts I2 to the beams.

First describing the construction an mode of operation of the upperv unit A: This comprises a horizontal base plate 20 which is supported in the frame structure upon a pair of transverse channel beams I9 which, in turn, rest at their ends upon and are bolted, as at I5 in Fig. 6, to the beams 1-1. The base plate 20 is formed at opposite sidesy with depending flanges I8 and these t between and are bolted, as at I8a, to the beams I9. Secured centrally to the under side of the plate 20, is a gear housing I6, removably attached to the base by means of bolts 2l as seen best in Figs. 2 and 6. 'I'his housing serves a. purpose presently described.

Mounted on this base plate 20, and held against rotation thereon, is the lower grinding stone 22 of this unit. As herein illustrated, the lbase 20 is circular and has a plurality of radial ribs 20a over which the stone is fitted. Also, the stone is fitted within an upstanding annular flange or shoulder 23 on the base 20 concentrically about the axis of the unit. Also a circular plate 24, as an aid in the initial crushing of material is counter-sunk in the top surface of the stone, coaxially thereof and flush with its top surface. Anchor bolts 25 extend downwardly through the plate and stone and at their lower ends are threaded Ainto the base plate 20 to cooperate with longitudinal ribs 20a cast on the base plate to hold the stone and plate 24 securely in place.

Encircling the base 20, concentrically thereof and outwardly spaced from the flange 23 but of higher extent, is a rim flange 26. These flanges together form an annular trough 21 about the stone for the reception of the ground material issuing from between the stones. In the grinding of cocoa nibs, and the like, the ground material will issue from between the stones in the form of heavy liquid or liquor, andthe base of this trough has outlets 28 communicating with conduits or tubes 29 through which the liquor" or ground material is conducted from the upper to the lower unit of the machine.

A -Formed centrally of the stone mounting base plate 20, is a bearing 30, through which the lower end portion of a vertical, tubular spindle shaft 3| is slidably fitted, and which lower end portion also extends downwardly through the housing I6 and is slidably contained within an opening 32 in \the base of the latter. At its upper end, the 76 spindle shaft 3| is fitted slidably within a cen# Y tral bearing `33 of the top spider 3,' permitting vertical adjustment ofshaft 3| for a purpose presently explained.

Formed on the shaft 3|. near its lower end, is an encircling shoulder 35. Also, on the shaft 3|, at an interval spaced above the shoulder 35, is an encircling collar 36 fastened to the shaft to serve as the medium of support for a tting 31 that forms the mounting hub of the upper stone 36 of this unit. This upper stone 39 isl rigidly fixed about the fitting 31 concentrically thereof,`and is held horizontally disposed thereby with its lower surface in a plane parallel with the plane of the top surface of the next lower stone. Also, this stone is of a diameter equal to that of the Vtwo lower stones of the unit and it has an encircling angle iron band 40 tted and secured about its upper peripheral edge. Studs 4| are fixed to this band 40, and they extend vertically and slidably through guide bearings 42 in the spider frame 3. This provision of studs holds the top stone against rotative movement, but without hindrance to a vertical adjustment; the purpose of which vpres- Aently will be explained.v Coiled springs 43 are located under compression about Vthe end portions of the studs 4|, extended beyond the spider, and they bear at their upper ends. against yokes 44 mounted on the spider, and at their lower ends -bear against nuts 44a adjustably threaded onto the studs, thereby, through the studs, to yieldingly urge the top stone toward the next lower stone with a pressure that may be increased or decreased, as desired, by adjustment of the nuts 44a along the studs, thus to regulate the grinding pressure.

To provide for an accurate, equal and simull"taneous adjustment of all nuts 44a, the nuts are in the form of small pinion gears, as will be understood best by reference to Fig. 3, and a ring gear R is disposed concentric of the machine in mesh with all adjusting nuts of the stone, thereby providing that, by a rotative action of the ring gear, all the nuts 44a.may be quickly adjusted tov place the springs under any desired degree of compression.. The ring gear, as will be observed by reference to Fig. -2, has flanges 1' extended fromits top and `under surfaces to embrace top and bottom surfaces of the nuts so that the ring gear will be retained in mesh therewith at all times. A If desired,'sprocket nuts could replace the gear nuts and a sprocket chain belt'replace the ring gear, with the same result.

Fixed coaxially to the under side of 31 and countersunk in the stone, to be ush with its under surface, is a ridged plate 45, which coacts with a similar plate 41 on 'the next lower stone and between which plates 'the material to be ground -is initially received for crushing prior to grinding by the stones.

Interposed between the stones 22 and 33 is the intermediate stone 49. This is mo'unted by 'a hub fitting 46` which has a central bearing portion 46a revoluble about the vertical spindle shaft 3|. The stone is held rigid on the supporting fitting 46 between face plates 41 and 46 which are counterl sunk in the upper and lower faces of the stone,

respectively, and are riveted to the top and bottom edges -of the tting 46. Thesefplates are grooved,l or ribbed, to c oact with theplates and 24 of the top and bottom stones to effect. the

initial crushing orfgrinding operation of the material entering the machine, and it will be observed that au-the grinding plates are/of annum :form andthat the openings through Aplates 45 and the tting that of the other stones of th`e set and it has a driving ring gear 45a fitted and secured thereto. The ring gear base, together with the outer rim and the connecting web, forms a trough" 50 about the stone, and this is adapted to receive therein the ground material issuing as a heavy liquid from between the upper and intermediate stones. The trough base is provided at intervals with discharge openings 5| and the ground material received into the trough is wiped into these openings lby fins or paddles 52 that are xed to the encircling band 46 on stone 36 and which depend into the troughy and scrape therealong as the stone revolves.

Material to be ground enters the machine at the top through a delivery tube 55 coaxial of the unit. This tube leads into a conical housing 56 which, in turn, is fastened in a closed joint about its lower peripheral edge to the hub portion of the spider 3. This hub portion, about the bearing 33, has passages 51, which receive the material from the housing 56, discharging downwardly into passages 56 formed in the fitting 31 which mounts the stone 36. if

To insure an even distribution into the machine of material received from tube 55, a conical distributor 59 is located axially of and directly beneath and spaced from the lower end of the tube 55. 'Ihis distributor is ixed on a vertical shaft 60, revolubly contained coaxial of spindle shaft 3| and extending to the lower end of the latter where it has a driving belt pulley 6| fixed thereto. The lower end of the shaft 6ll-is`icontained revolubly in a bushing 62 that is threaded into a central bearing 63 of a spider frame 64 fixed to the lower face of the housing` I6. The bushing 62 has a hand wheel 65 formed thereabout whereby it may be rotated to raise or lower the bushing. The bushing bears at its upper end against wardly discharging passage 63 coaxially of the tion ofthe tting 31. The lower ends of the passages 53 partiallyl overlapl an annular, down'- hub fitting 46 of the central stone 49 and also partially overlaps vthe annular grinding plate 41 of the central stone. Thus, through the passage 53, material is fed between the plates 45 and 41 to the coacting grinding surfaces of the stones 33 and 49 and also to the passage 63 for delivery between'the plates 24 and 46 4to the colacting grindingsurfaces of the stones 49 and. 22.

It will be observed that the lower end of the annular passage 66' opens directly to the grinding surfaces between the plates 24 and 43 and the delivery of material to ythese surfaces is facilitatedA by the beveiing of the inner edge of the plate 43, as shown best in Fig 2, and the outward feeding or the material" betwn stones is fui-ther uw dited by reasonl of a certain ridging and groovlng of adjacent surfaces, as is indicated in the top surface of the stone I9 a5 seen in Fig. 5.

It will here be mentioned that while the manner of grooving the coacting surfaces of the stones and grinding plates for centrifugal feeding or moving of material forms no part of the invention as applied to the machine of Figs. 1 and 2, it is intended that the grooving should be of a character to effect a progressive and definite feeding of material from its point of reception outwardly to the point of delivery. Fig. 5 illustrates a preferred manner of grooving a crushing plate and stone, but it is to be understood that this is only one of a plurality of methods of grooving that may be employed; the stone here being shown as having the main furrows f of radial direction and the spirally directed feather edged cutting grooves g. v

Adjustment of the spacing of the stones for purpose of regulating thefineness of grind, and also a spacing thereof to permit ready feeding of material between the stones at the start of a grinding operation, is provided for through the mediacy of the spindle shaft 3|, as will now be described.

It will be observed by reference to Fig. 2, that a worm gear 10 is threaded onto the lower end of shaft 3| and that this gear is .fitted rotatably between the lower end of the hub 30 of plate 20 and the lower wall of the housing I6. Thus, the gear 10 supports'the shaft 3l and incidentally may, at a certain adjustment, support the upper and intermediate stones by reason of the collars 36 and 35 on the shaft. Meshing with gear 10 is a worm 12 on a shaft 13 extended to one side of the machine, see Figs. 1 and 6, and there equipped with a crank 15, or other means, whereby rotary adjustment of gear 10 may be made. By rotary adjustment of the gear 10 in one direction, the shaft 3| may be raised, and incident to this adjustment, the collar 36 will engage fitting 31 and effect the lifting of top stone 38 to a substantial clearance above the intermediate stone 49. Then, a fartherV lifting of the shaft 3| will effect the lifting of the intermediate stone 49 above the surface of the lower stone 22 by reason of the collar 35 coming into lifting contact with an anti-friction bearing contained on the mounting hub portion 46a of the fitting 46 which mounts the central stone 49.

It willl here be stated thatstarting of the machine, if empty, should be done with the stones spaced apart so that the material may feed between them. Then the stones with material between them are lowered into grinding relation.

Referring now to the lower unit B. This comvprises stones'in triplicate, designated, respectively, by reference numerals 8|, 82 and 83, coaxiallyL mounted lby a vertical spindle shaft 84 that is alined with the axis of the upper unit. The shaft 84 is fixed at its upper end in av central bearing 85 in the spider frame I, and at the lower end is fixed in a bearing 86 in the base wall of a gear housing 81 presently described. Y

The lower stone 83 of this unit is mounted by a horizontally disposed base plate 9| which rests upon a pair of 'spaced'parallel cross beams 89-89 which, in turn, rest at their ends upon the channel beams I0-|0 to which they are secured by bolts as seen in Figs. 2 and\'1. The base plate 9| is formed on its under side with depending flanges 88-88 which t against the inner vertical faces of the cross beams 89-89, and are secured thereto by'fbolts 88'.

The stone mounting base plate 9| is-formed with a central hub portion about which the stone is fitted, and it also has an upstanding peripheral.

bolted concentrically to the under side of the base plate by bolts 92 and its'purpose is to house the stone adjusting gears presently to be described.

The upper stone 8| of the unit is mounted by a hub fitting 96 including a central bearing 96a that receives the vertical shaft -84 slidably therethrough. This lfitting has vertical passages 81 therethrough about the bearing, which receive directly thereinto the partially ground material from the upper unit, delivered thereto through the tubes 29. Also, there is an angle iron band 98 fitted about the upper peripheral edge of the stone, and vertical studs 99 are fixed to this band and extended slidably through bearings |00 in.

the spider 4 to holdl the stone against rotation,

bear against yokes |02, fixed to the spider and downwardly against gear nuts |03 on the studs to urge the stone yieldingly toward the next lower stone; adjustment of pressure being provided for in the adjustment of the nuts |03, thereby to. regulate the grind, by a ring gear R as previously described.

The central, or intermediate stone 82 of this set is mounted on a hub fitting |05 that is revoluble about a sleeve |06 which, in turn, is rev.- olubly and slidably fitted about the tubular shaft 84.v The upper end of the sleeve I 06 is formed with inclined cam surfaces I|0 shown in Fig. 8, which restagainst complementary ysurfaces III on the under end face of the hub por- I tion 96a. The lower end of the sleeve |06 extends into the gear housing 81 and there has a supporting worm gear wheel ||2 keyed thereto. An adjusting worm 'II3 on av shaft IM meshes with the gear II2, and this shaft extends from the housing 81 and is provided with a crank Ill or the like, for rotary adjustment of gear II2.

The upper end surface of the hub portion .of gear wheel ||2 has inclined cam surfaces ||2,

vsee Fig. 9, engaging coacting cam surfaces IIS' on a plate I I5 that is supportedthereon; the plate having a central opening for passage of the` sleeve. I 06 and having radial legs I|1 contained in vertical guidesl I|8 integral with the under face of base plate 9|. Ball thrust bearings |20 are interposed between the plate I|5 and the l lower end of a downwardly extended hub sleevel faces II2' on the upper face of the hub of gear II2, coacting with cam surfaces ||5 of plate II5,

Thus, an adjustment of the worm,v

will cause alifting action of the plate to effect a similar lifting of thecasting |05 and the intermediate stone, to clear the latter from the lower stone.

Itis important in'this adjustment that the lift to the-middle stone coming to grinding position.

The adjustment of the stones for this mode of operation is accomplished by the particular cam design which permits of a continuous rotation of the worm wheel in the same direction. That is, rotation thereof to a certain extent effects the' lifting of the stones into spaced relation in their proper sequence. Then,` rotation of the wheel through the remaining part of a turn likewise lowers them, in proper sequence, to initial position. The cams might be of various design to accomplish this purpose, and the present invention is not concerned particularly with the design except to the extent that it provides for thelifting and lowering of the stones in proper sequence and tothe extent desired.

A ring gear ||9 encircles and is fixed to the central stone 82 and this, as presently described, is rotatably driven to rotate the stone for a grinding operation; the other stones, being held against rotation as was previously described.

Material that is fed to the lower unit through the tubes 29-29 and received as a heavy liquid in the annular, hub passages Eil, first is fed to the adjacent grindingv surfaces of the stones 8| and 82, passing thereto through the outwardly converging annular space between them which is best shown in Fig. 2.

The ground material, in passing outwardly between stones 8| and 82, finally feeds into an encircling trough |28 formed by the base and outer ange of the ring gear i I9, and passes therefrom through openings |30 in the web of the gear into a circular receiving trough iti underlying the gear and from which conduits m2 lead into the outer ends of horizontal tubes |33 mounted radially of the base 9| with their inner ends opening into an annular chamber |35 of the hub bearing 95. Feed screws it are contained in the tubes |33 and are revolubly driven in a dithe receiving space between the grinding surfaces of thecentral and lower stones. The driving means here shown for the feed screws y|38 comprises belt pulleys i39 fixed on their outer ends and about which pulleys driven belts lli@ operate.

The hub portion of casting it is formed with radial fins ||l5a and these are inclined relative to the direction of rotation so as to act as outward feeders of the material that is forced upwardly from chamber |35, to the space between stones, thereby facilitating distribution of liquor to the grinding surfaces.

Ground material passing outwardly from between these latter stones 82 and 33 is caught in a trough Mi that encircles the lower stone and is conducted therefrom to a point of use, through troughs or tubes as lat |42, which lead from the trough itl,

Power for driving the machine is applied through a vertical, rotatably driven shaft |50 sup rted at one side of the machine, as shown in Fig. 4, in bearings |5| and |52. On this shaft are gear pinions |53 and IEB meshing, respectively, with the ring gears a and -i I9 whereby the stones I9 and 82 are rotated.

A lso, on the vertical shaft |55 alined with belt wheel 6| and a belt |56 operates about these wheels to drive the distributor shaft 60.

is a belt wheel:

A cross shaft |58, horizontally mounted by bearings IBB-|' and IGI-ISI', as seen in Fig. '1, is driven by a spiral gear connection with shaft |50 as designated at |62 in Fig. 7. This cross shaft'is equipped at its ends 4with belt wheels "i3- |64 alined with the belt wheels |39-I39 on the ends of the feedscrews |38 and the belts |130 operate thereover to drive the screws as prebe composed of carborundum, or a like material,

since this has been found to be very satisfactory for the intended purpose. However, stones of the usual, or of other composition may be used to advantage.

Briefly described, the mode of operation of the above described machine is as follows:

Assuming first that the coacting stones of the two units, A and B, have been adjusted into spaced relation for reception of material, the material to be ground is admitted to the upper unit of the machine through the supply tube 55 and is controlled in its flow by vertical adjustment of the feed cone distributor 5S, provided for by theA hand wheel S5. The material passes into the passages 5l of the top spider and from there is delivered into the passages 58 of the hub fitting 3l of the upper stone 33. Part of the material passes downwardly into the passages 68 of the hubv of the intermediate-stone dii. The material thus fed to the machine flows outwardly between the coacting surfaces of the plates and three stones. Then, by manipulation of the adjusting gear it, the stones are adjusted into grinding relation. The material ground in the upper unit is emitted from between the surfaces of the upper stone and the intermediate stone into the trough formed by the ring gear a, and that emitted from between the intermediate stone and the lower stone is received within-the annular trough 21 encircling the lower stone. This latter trough also receives the material from the upper surfaces through the openings 5| in the ring gear. The material received by the trough 2l ows as a heavy liquid through the tubes 29 to the lower unit for its' second reduction.

The grind in the rst unit is regulated to a certain extent bythe surfacing of the stones and by the pressure applied thereto through the mediacy of the springs lid.

Prior to reception of material from tubes 29, the stones of the lower unit B are adjusted to spaced relation. When sufficient material has been delivered between the upper and intermediate stones of this unit to prevent actual contact, they are then lowered into grinding relation. The ground material emitted from between the upper stone and intermediate stone of this unit is re,- ceived by the trough formed by the rin'g vgear i9 and from there passes into the trough I3| and nally into the conveyor tubes |33 through which it is forced by the feed screws into the chamber |35 to feed upwardly from this chamber to the Space between the grinding surfaces of the intermediate stone and the lower stone. These two stones are then lowered into grinding relation and the ground material is emitted from between them into the encircling trough Ml, from which it is conducted to its point of use.

vcus

plished by use of three stones, whereas, in prior art machines, four stones are required.

In view of the fact that fewer stones are required, it is apparent that the weight of a machine may be materially reduced and without reducing the capacity of number of reductions possible by use of the machine. Furthermore, the cost of providing machines of this character is materially reduced. y

It is apparent that in this type of machine, the stones may be arranged in multiples of three or more, and that it then is only a matter of arranging the proper feed to accommodate the cooperating surfaces of adjacent stones. In multiples of two or more, arranged after the fashion of the stones in unit A, it would be only a matter ofcontinuing the feed to supply all surfaces. In multiples of two or more, with a feed arranged as in unit B, wherein the material is delivered successively between the grinding surfaces of successive stones, it would be only a matter of providing for feeding this material from one set to another, and this might be accomplished for multiples of four or more in the same manner as is illustrated in- Fig. 2, or, if assuming that certain stones are grooved in a manner to cause the material to feed from the Vupper set of stones inwardly between the surfaces of the next set, then the progression -of material would be continually downward, but

would ow outwardly and then inwardly in successive grindings as it progressed from the upper to the lower stones.

In the present construction, as was an object of the invention, the stones are held in parallel relationship by their slidable mounting on the central shaft, and are urged yieldingly together under an adjustable pressure by the provision `of the springs associated with the upper stone. 'I'his is believed to be a novel feature in view of the fact that, heretofore, it has been the common practice to mount one of the stones loosely for universal adjustment thereby permitting it to automatically accommodate itself to unevenness of wear on 'one or both of the stones.

Various modifications and alternatives will now be described:

In Fig. 10 we have illustrated a type of machine, known as an under fed mill. In this construction, w`e utilize a plurality of horizontal stones, arranged in vertical, coaxial alignment about a centraldriving shaft |10. The shaft is revolubly contained at upper and lower ends, respectively, in bearings 1| and |12 of a suitable frame structure. The five stones, herein shown, and designated by reference characters |13, |14, |15, |16 and |11 may be of the usual form of construction for centrifugal movement of ground material. The stones |18, |15 and |11are held against rotation by guides |18 fixed thereto and slidable along vertical shafts |80 rotatably supported in the frame structure. Also, the stones of this set may be lifted into spaced adjustment by means of collars |8| that are fixed on the vertical shafts |80. fThe collars I 8| which are to lift the nonrotating stones |18 and |15 are adapted to be lifted by the shafts |80 againstthe guide blocks |18 of these stones, while the collars |8|', which are tol lift the rotating stones, comprise sleeve por- `tions which have bearings |19 rotatable thereon and arranged to be lifted by the collars into,l.ifting abutment with shoulder bands |8| a that encircle and are fixed to these stones. -v

In o rder to insure a pressure -of the series of stones" toward each other sufficient for the grinding operation, coiled springs |83 are'located about the shafts |80 to bear against collars |84 on the shafts, and against the guide lugs |18 which are fixed to the uppermost stone.

As here shown, the stones |14 and |16 are keyed to the shaft |10 for rotation thereby, and this shaft may also be used if desired to effect an adjustment of the stones into spaced relation by the following means: Keyed on shaft |10, near its upper end is a vgear |90, and keyed on the shafts |80 are gears |9| of like size meshing with gear. |90. A clutch disk |95 is fixed on gear '|90 and a clutch drum |96 is slidably keyed on shaft |10 and movable by a shiftv lever |91 into holding contact with the disk to cause the gear |90 to be rotated. This causes rotation of gears I 9|,and shafts |80, which latter are threaded at their lower ends into the frame structure, as at |98 in Fig. 10. Rotation of shafts |80 causes -them to travel upwardly and thus to cause the collars |8| to engage in succession with shoulders of the stones from top to bottom of the set, thus to lift the stones into spaced relation. A spring |99 urges the clutch drum to non-drivingv position when released by lever |91.

'I'he material received as a liquid to be ground is here forced through a conduit |82, upwardly through a passage l|83 in the hub mounting of the lower stone, into theintervening space between the grinding surfaces of stones 1/6 and |11. From this space excess material is forced upwardly, by reason of the feeding pressure, into the intervening spaces between the upper stones.

To provide for this upward flow, the mounting hub |85 of stone |14 has passages |86. Stone |15 likewise has a central passage |81 and the.

hub member |88 lof stone |16 has passages |89.

In this construction of Fig. 10 there is no over-- flow opening at the top of the unit and thereforel the rate of delivery of ground material would be 'i governed by regulating the flow through pressure f feed pipe |82.

In Fig. 11 there has been illustrated, in cross section, another modication of a grinding mill employing three stones for two reductions, and whereby both a centrifugal and a centripetal movement of material is accomplished, thus to simplify the machine. This machine comprises base supports 2| 0-2|| which mount an enclosing housing 2|2 for the three stones which are designated, respectively, by reference numerals 2| 5,

2| 6 and 2|1. These stones are in vertical axial alinement and the upper and lower stones are held against rotation within the housing while the intermediate stone is revolubly driven. As will be observed, the upper stone has a hub casting 220 with vertical passages 22| into which material is delivered from asupply tube 222. From the passages 22|, the material is delivered into the outwardly converging annular space 223 between the stones 2|5 and 2|8 for grinding in its centrifugal movement to the peripheryof the stones. On issuing from between the upper set of stones, it flows downwardly and, by the enclosing housing, is delivered into the annular. inward- 1y converging space 224 between the stones 2|6 and 2|1 for a centripetal movement and on being emitted from between these stones passes into discharge openings 225 of a hub casting 226 in the lower stone and is delivered therefrom to a housing 221 for delivery from the machine.

In the mechanism illustrated, the central stone .has a hub fitting 228 revoluble on a central, tu-

bular shaft 229, the latter being revolubly conin a bearing in the base castingv 228. 'I'he stone arrasar;

2 I6 also has a ring gear 246 fitted thereabout and meshing with a driving gear 23| on a shaft 232.

Vertical adjustment of the upper and intermediate stones is providedfor in the vertical movement of their mountings. Sleeve 229 is adjustable through themediacy of a worm gear 236 threaded on its lower end, and likewise, a vertical adjustment of sleeve 230 by a worm gear 233 threaded onto its lower end.

It is to be understood that in this, as well as in other modifications of the mill, the driving of the stones, their mode of adjustment, the feeding and delivery of material.' etc., may be accomplished in various ways and therefore it' is not the intention that the disclosures should in any way restrict the claims to the details shown. However, in the mills using the centripetal feeding of material, it becomes necessary to groove, or process the stones in a manner that will not only overcome the tendency to feed or force the material outwardly by reason of centrifugal action, but which will actually induce an inward now, such for instance as is required reference to the stones 2|6 and 2H in Fig. l1.

In Fig. 14, there has been illustrated a method of grooving stones to effect the centripetal movement of ground material, and it is intended that Ythis shall be applied to the machine of Fig. 11. In Fig. 14, 245 and 246, respectively, designate upper and lower stones of a pair arranged for centripetal feeding of material and the arrows placed thereon designate their direction of relative rotation. Each stone is provided about the peripheral portion of its grinding surfacev with relatively large furrows 248 all extending circumferentially in the same direction, and tapered toward their inner ends, and opening toward the direction of rotation as effective collectors of material. The mouths of the furrows which open to the periphery of the stone are quite wide to facilitate scooping up the material to be ground. Between the furrowed area of the disk and the central part, the disk is closely grooved. These grooves 250 are slightly volute in direction and receive the material from the furrows to deliver it toward the axis of the stones, by reason of pressure of material gathered by the large mouths of the furrows and grooves.

It will here be explained that the direction of grooving in the surface of each stone is the same, but, since one is inverted and placed face down on -the other, the direction of grooving in one then angularly crosses that of the other. Therefore, when the stones are rotated in opposite directions, or when one is rotated and the other held stationary, the grooving in one has va sort of shearing action across the grooving ofthe other toward the central axis of the stones and this effects an inward conveyance or pressure against the material as will be quite obvious. The normal centrifugal tendency is overcome by this manner of grooving and when both stones are rotated, in opposite directions, the speed'of rotation may be reduced to one-half that required where only one is driven. Feeding is facilitated also due to the fact that in this type of mill, the mouths of the furrows arefiloode'd with the material to be ground by reason of -the enclosing housing, such as the housing 2I2 in the device of Fig. 11.

In Flgs./12.and 13 is illustrated what is identied as avertical stone mill. .In'this arrangement there is a plurality of` u' its, X, Y, Z, successively t at lower elevations,l and the stones in each of the several units-'are supported on a horizontal axis, in a. suitable frame. In the detailed illustration with y of one of the units, as seen in Fig. 13, the stones are designated by reference characters 26|, 262 and 263. The outer stones 26| and 263 are stationary, but the center stone is rotatably driven by its supporting shaft 266, mounted on the frame structure. The material to be ground is fed under pressure into the space 'between the stones 26l and 262 from a supply pipe 261, which opens into the tubular hub 269 which mounts the stone 26|. Part of the material delivered passes through openings 268 in the hub portion 26811 of the central stone into the receiving space between the center stone and the opposite side stone 263. A housing 210 surrounds the stones and receives the ground material which is emitted from between the stones. This material is discharged through a delivery pipe 21|. Any suitable frame structure may be provided to support the driving shafts of the units and the shafts may be driven by any suitable means.

It will be mentioned here that machines of this latter type may be made in single units or in a series of units, as in Fig. 12, and material delivered by gravity or forced flow from one to the next succeeding one.

In each of the machines described, provision has been made for utilizing both sides of intermediate stones for a grinding operation. Thus, the object of reducing weight, size and cost has been aecomplished. Furthermore, a more expeditious handling of material is made possible by the feed devices shown and also in the provision made for centripetal movement where this is desired.

Having thus described our invention, what we claim as new therein and desire to secure by Letters Patent is:

l. A grinding mill comprising a series of three or more parallel faced stones arranged in vertical coaxial alinement and yieldingly in face to face contact, means for causing relative rotation of adjacent stones, means for introducing material between opposed faces for grinding and an axial support for the stones movable in its axial direction and having means thereon to cause the stones to be lifted into spaced relation successively from the upper stone downwardly and to be lowered into grinding relation successively from the lower stones upwardly.

2. A top feed grinding mill comprising a frame structure, an axial shaft supported vertically thereby for longitudinal adjustment, a series of parallel faced grinding stones mounted about the shaft for relative rotation and successively in face to face opposition, each stone having a hub bearing fitted to the shaft whereby the stones are held rigidly and operatively in parallel relation, means for eecting an upward longitudinal movement of the said shaft, and shoulders on said 'shaft engageable with the hub bearings of the stones when said shaft is adjusted upwardly to effect the lifting of the stones of the series into spaced relation successively from the upper stones downwardly, and when the shaft is lowered to lower the stones into grinding relation successively from the top stone downwardly.

3. A device as in claim axial shaft is keyed vagainst rotation Vin the frame and wherein the means for effecting the longitudinal travel of said shaft comprises a gear wheel threaded thereon and held in the 2 wherein the said frame against movement in a direction axially of the shaft, and means is provided for rotating reason of its threaded connection.

which is revolubly vIl() 4. In a grinding mill of the character described, three grinding stones arranged coaxial- 1y about a vertical axial member, successively in face to face contact, means for effecting a relative rotation of adjacent stones for the grinding of material between opposed faces, means for feeding material through the upper stone to the coacting faces of the` central and upper stones for reduction and for a centrifugal discharge. of material, means for collecting the material as it is emitted from between the said central and upper stones, and means for delivering the collected material upwardly through the lower stone to the coactingsurfaces of the central and lower stones for a further reduction.

5..In a grinding `mill of the character described, three parallel faced grinding stones arranged coaxially about a vertical axial member, successively one above the otherA and yieldingly in face to face opposition, means for effecting a relative rotation of adjacent stones for the reduction of material introduced between opposed faces; the upper stone having a hub mounting with openings therethrough for the delivery of material to the enacting surfaces of the upper and central stones for reduction and centrifugal delivery, a mounting for the lower stone having openings directed upwardly therethrough and communicating with the space between `the grinding faces of the central and lower stones, and means for effecting a forced delivery of material from the ilrst set of faces upwardly through the said openings to the second set of grinding faces -for centrifugal delivery therefrom.

6. In a grinding mill of the character. described, a series of parallel faced grinding stones arranged coaxially about a vertical, tubular axial member, and successively in lface to face opposition; said stones having mounting hubs fitted to said axial member, andhaving registering annular Ifeed passages therethrough vfrom face to face of the stones and through which material may be supplied to all the grinding surfaces, the annular passages being in communicating relationship for continuous flow of material therethrough to the several grinding surfaces, a hopper, a supply tube entering said hopper, a distributor disk supported below the delivery end of the tube, a revolubly driven supporting shaft for said disk, and means for longitudinally adjusting the shaft to move the disk toward or from the tube outlet to determine the'` delivery of material therefrom.

7. In a mill of the character-described, a series of three grinding stones arranged coaxially of afvertical axial member yieldingly in face to face opposition, means for effecting avrelative opposite rotation of the central stone with reference to the upper and lower stones, means for feeding material between the coacting surfaces of the central and upper stones at a central point for centrifugal delivery, means for feeding the material from the first set of stones between the opposed surfaces of the lower set of stones for asecond reduction and centripetal delivery; the opposed surfaces of the coacting stonesvhaving grooves therein from their outer to the medial portions arranged with those of one surface angularly crossing those of the other and so directed that relative rotation of said stones causes coaction of the grooved surfaces whereby the direction of delivery is determined.

LEONARD DOTZER. GEORGE D. HUGO. 

